[PATCH] gpu: host1x: Free the IOMMU domain when there is no device to attach

Discussion:

Paul Kocialkowski

2017-07-10 19:33:05 UTC

When there is no device to attach to the IOMMU domain, as may be the
case when the device-tree does not contain the proper iommu node, it is
best to keep going without IOMMU support rather than failing.
This allows the driver to probe and function instead of taking down
all of the tegra drm driver, leading to missing display support.

Signed-off-by: Paul Kocialkowski <***@paulk.fr>
---
drivers/gpu/host1x/dev.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/host1x/dev.c b/drivers/gpu/host1x/dev.c
index ac65f52850a6..f296738d0de8 100644
--- a/drivers/gpu/host1x/dev.c
+++ b/drivers/gpu/host1x/dev.c
@@ -186,8 +186,13 @@ static int host1x_probe(struct platform_device *pdev)
return -ENOMEM;

err = iommu_attach_device(host->domain, &pdev->dev);
- if (err)
+ if (err == -ENODEV) {
+ iommu_domain_free(host->domain);
+ host->domain = NULL;
+ goto iommu_skip;
+ } else if (err) {
goto fail_free_domain;
+ }

geometry = &host->domain->geometry;

@@ -198,6 +203,7 @@ static int host1x_probe(struct platform_device *pdev)
host->iova_end = geometry->aperture_end;
}

+iommu_skip:
err = host1x_channel_list_init(host);
if (err) {
dev_err(&pdev->dev, "failed to initialize channel list\n");

--
2.13.1

Mikko Perttunen

2017-07-11 06:43:43 UTC

Permalink

Thanks for the patch, didn't consider this case. I really need to get
together some system to automatically test on multiple platforms.. :)

Post by Paul Kocialkowski
When there is no device to attach to the IOMMU domain, as may be the
case when the device-tree does not contain the proper iommu node, it is
best to keep going without IOMMU support rather than failing.
This allows the driver to probe and function instead of taking down
all of the tegra drm driver, leading to missing display support.
---
drivers/gpu/host1x/dev.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/host1x/dev.c b/drivers/gpu/host1x/dev.c
index ac65f52850a6..f296738d0de8 100644
--- a/drivers/gpu/host1x/dev.c
+++ b/drivers/gpu/host1x/dev.c
@@ -186,8 +186,13 @@ static int host1x_probe(struct platform_device *pdev)
return -ENOMEM;
err = iommu_attach_device(host->domain, &pdev->dev);
- if (err)
+ if (err == -ENODEV) {
+ iommu_domain_free(host->domain);
+ host->domain = NULL;
+ goto iommu_skip;
+ } else if (err) {
goto fail_free_domain;
+ }
geometry = &host->domain->geometry;
@@ -198,6 +203,7 @@ static int host1x_probe(struct platform_device *pdev)
host->iova_end = geometry->aperture_end;
}
err = host1x_channel_list_init(host);
if (err) {
dev_err(&pdev->dev, "failed to initialize channel list\n");

Jon Hunter

2017-07-18 09:09:45 UTC

Permalink

Hi Mikko,

Post by Mikko Perttunen
Thanks for the patch, didn't consider this case. I really need to get
together some system to automatically test on multiple platforms.. :)

We already have the infrastructure in place to do this, however, at the
moment we are just making sure the platforms boot. Something like this
we should be able to catch, even if we don't explicitly test display/hdmi.

I was thinking that we could parse the /dev and /sys file-systems to
ensure that devices for a given platform are present after boot. I am
not sure if there is a good way to do this, but if you have any
thoughts, then I am willing to add more testing.

What is interesting about this case, was that there were no specific
error messages that indicated this had broken AFAICT.

Cheers
Jon

--
nvpublic

Paul Kocialkowski

2017-07-11 08:49:47 UTC

Permalink

Fixes: 404bfb78daf3 ("gpu: host1x: Add IOMMU support")

Post by Paul Kocialkowski
---
drivers/gpu/host1x/dev.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/host1x/dev.c b/drivers/gpu/host1x/dev.c
index ac65f52850a6..f296738d0de8 100644
--- a/drivers/gpu/host1x/dev.c
+++ b/drivers/gpu/host1x/dev.c
@@ -186,8 +186,13 @@ static int host1x_probe(struct platform_device *pdev)
return -ENOMEM;
err = iommu_attach_device(host->domain, &pdev->dev);
- if (err)
+ if (err == -ENODEV) {
+ iommu_domain_free(host->domain);
+ host->domain = NULL;
+ goto iommu_skip;
+ } else if (err) {
goto fail_free_domain;
+ }
geometry = &host->domain->geometry;
@@ -198,6 +203,7 @@ static int host1x_probe(struct platform_device *pdev)
host->iova_end = geometry->aperture_end;
}
err = host1x_channel_list_init(host);
if (err) {
dev_err(&pdev->dev, "failed to initialize channel
list\n");

--
Paul Kocialkowski,

developer of free digital technology and hardware support

Website: https://www.paulk.fr/
Coding blog: https://code.paulk.fr/
Git repositories: https://git.paulk.fr/ https://git.code.paulk.fr/

Marcel Ziswiler

2017-07-11 14:37:35 UTC

Permalink

Post by Paul Kocialkowski

Fixes: 404bfb78daf3 ("gpu: host1x: Add IOMMU support")

Post by Paul Kocialkowski
org>
---
drivers/gpu/host1x/dev.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/host1x/dev.c b/drivers/gpu/host1x/dev.c
index ac65f52850a6..f296738d0de8 100644
--- a/drivers/gpu/host1x/dev.c
+++ b/drivers/gpu/host1x/dev.c
@@ -186,8 +186,13 @@ static int host1x_probe(struct platform_device *pdev)
return -ENOMEM;

err = iommu_attach_device(host->domain, &pdev-

dev);

- if (err)
+ if (err == -ENODEV) {
+ iommu_domain_free(host->domain);
+ host->domain = NULL;
+ goto iommu_skip;
+ } else if (err) {
goto fail_free_domain;
+ }

geometry = &host->domain->geometry;

@@ -198,6 +203,7 @@ static int host1x_probe(struct platform_device *pdev)
host->iova_end = geometry->aperture_end;
}

err = host1x_channel_list_init(host);
if (err) {
dev_err(&pdev->dev, "failed to initialize channel
list\n");

Please note that this does no longer cleanly apply after Mikko's 'gpu:
host1x: Refactor channel allocation code' commit from June 15 already
applied to current -next. Other than that

Tested-by: Marcel Ziswiler <***@toradex.com>
Tested-on: Apalis TK1, Apalis T30, Beaver, Colibri T30, Jetson-TK1

Finally graphics working again, thanks guys!

Paul Kocialkowski

2017-07-11 14:44:14 UTC

Permalink

Post by Marcel Ziswiler

Post by Paul Kocialkowski

Fixes: 404bfb78daf3 ("gpu: host1x: Add IOMMU support")

Post by Paul Kocialkowski
.
org>
---
drivers/gpu/host1x/dev.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/host1x/dev.c b/drivers/gpu/host1x/dev.c
index ac65f52850a6..f296738d0de8 100644
--- a/drivers/gpu/host1x/dev.c
+++ b/drivers/gpu/host1x/dev.c
@@ -186,8 +186,13 @@ static int host1x_probe(struct
platform_device
*pdev)
return -ENOMEM;
err = iommu_attach_device(host->domain, &pdev-

dev);

- if (err)
+ if (err == -ENODEV) {
+ iommu_domain_free(host->domain);
+ host->domain = NULL;
+ goto iommu_skip;
+ } else if (err) {
goto fail_free_domain;
+ }
geometry = &host->domain->geometry;
@@ -198,6 +203,7 @@ static int host1x_probe(struct platform_device *pdev)
host->iova_end = geometry->aperture_end;
}
err = host1x_channel_list_init(host);
if (err) {
dev_err(&pdev->dev, "failed to initialize channel
list\n");

host1x: Refactor channel allocation code' commit from June 15 already
applied to current -next. Other than that

Good to know! I intended this patch for fixing 4.12 stable, so I'm not
even entirely sure it should land in next. The patch that fixes the
device-tree to actually enable the iommu should be merged in priority.

If that is the case and anyone wants this patch rebased to next, feel
free to let me know and I'll send a rebased version.

Post by Marcel Ziswiler
Tested-on: Apalis TK1, Apalis T30, Beaver, Colibri T30, Jetson-TK1
Finally graphics working again, thanks guys!

Yay! :)

Mikko Perttunen

2017-07-11 17:09:56 UTC

Permalink

Post by Paul Kocialkowski

Post by Marcel Ziswiler

Post by Paul Kocialkowski

Fixes: 404bfb78daf3 ("gpu: host1x: Add IOMMU support")

dev);

- if (err)
+ if (err == -ENODEV) {
+ iommu_domain_free(host->domain);
+ host->domain = NULL;
+ goto iommu_skip;
+ } else if (err) {
goto fail_free_domain;
+ }
geometry = &host->domain->geometry;
@@ -198,6 +203,7 @@ static int host1x_probe(struct platform_device *pdev)
host->iova_end = geometry->aperture_end;
}
err = host1x_channel_list_init(host);
if (err) {
dev_err(&pdev->dev, "failed to initialize channel
list\n");

host1x: Refactor channel allocation code' commit from June 15 already
applied to current -next. Other than that

Good to know! I intended this patch for fixing 4.12 stable, so I'm not
even entirely sure it should land in next. The patch that fixes the
device-tree to actually enable the iommu should be merged in priority.
If that is the case and anyone wants this patch rebased to next, feel
free to let me know and I'll send a rebased version.

We should definitely have this for non-stable kernels too - it would be
a bit strange if the driver worked if IOMMU support wasn't built into
the kernel but failed if it was :) It can also be helpful for debugging
to be able to disable IOMMU just for host1x.

Post by Paul Kocialkowski

Post by Marcel Ziswiler
Tested-on: Apalis TK1, Apalis T30, Beaver, Colibri T30, Jetson-TK1
Finally graphics working again, thanks guys!

Yay! :)